Plate lock-up mechanisms for printing machines



W. F. HUCK Feb. 11, 1958 PLATE LOCK-UP MECHANISMS PRINTING MACHINES Original Filed May 29, 1950 um E Hum.

ATTORNEY PLATE LOCK-UP MECHANISMS FOR PRINTING MACHINES William- F. Huck, Forest Hills, N Y.

Original application May 29, 1950, Serial No. 165,029, now PatentNo. 2,694,976, dated November 23, 1954. Dividedandthisapplication February 2, 1954, Serial No. 407,766

2-Claims.. (Cl. 101-415.1)

Thisinvent-ion relatesto printing machines-and more particularly, to means for holding, tensioningand locking-up. a flexible printing, plate on the plate cylinder ofa rotary printing machine.

Many-dilferent types and'kinds of 'mechanisms have been devised for securing flexible printingplates to plate cylinders of printing machines. However, advances in the printing art have demanded greater and greater accuracies in printing with the resultthat the plate holding devices heretofore used have not always proved entirely satisfactory. Therefore, one of the principal objects of the present invention is to provide an improved plate holding .device for printing machines.

Another object of the invention is to provide an improvedplatelock-up mechanisrnin which the maximum available'force of a spring may be used to clamp-and tension the plate.

A furthertobject' of the invention is'to provide an improved plate lock-upmechanism in which both ends of the plate maybe accurately registered and gripped.

Other'important objects of'the invention will be apparent from the following specification and'appended claims.

This application'is a divisionof an application filed by me on May 29, 1950, Serial No. 165,029, now Patent No. 2,694,976.

In the accompanyingdrawings, which'form part of this specification: 7

Fignl is an elevational view of a portion of .a printing machine showing a plate cylinder equipped with a plate holding and lock-up mechanism embodying 'thepresent invention, portions-of the mechanism'having been cut away to show internal details.

Fig. 2 is a cross sectional view of a portion of the plate cylinder as'seen along the lines 2'2 of Fig. 1,'the means for tensioning the'trailing end of the plate being shown in the unlocked on open position, and

Fig. 3 is a composite, cross-sectional view of theplate cylinder, the right hand portion'of Fig. 3 being viewed along the line 3-'3 of Fig. 1, and the left'hand portion being viewed along the line 3-3"of the same figure.

In general, the feature which distinguishes the present invention from prior proposals dealing with the same problem; lies in the use of a spring forboth clamping the otherwise free end of the flexible plate and for exerting the desired wrapping tensionon'said plate, and inwhich the spring when in. its. plate. clamping :and-tensioning conditioning,v is. in. its state of: maximum .stress, rather than, asheretotoregin itsvrelatively -relaxed condition. This permits. the :use :of a shorter :etfective length of spring without-any. lossvof: useful :tensioningforce, andhence permits the invention to be applied to smaller plate cylindersr than would otherwise be; possible, or permitsa greater degree of. plate. clamping. and .tensioning' force to be applied-within the dimensional limits of any size cylinder.

Referring-,more in..detail, .to, the drawings," which accompany and formpart ofth-is.specification,-the numerals 112-11 indicate a-pair of side frames ofa printingmanited States Patent Ofifice Patented F eb. 11, 1958 These frames support a pair of bearing bushings 1212' that rotatably support a pair of journals 13-13 formed on opposite ends of a plate cylinder indicated generallyby the numeral 15. The plate cylinderlS comprises a pair of spaced end discs 1616', connected by a cylindrical shell 17, and having a gap 18, that extends longitudinally the total distance between the discs 16 and 16, which gap allows access to a plate lock-up mechanism, later to be described.

The plate-cylinder 15 carries a flexible printing plate 20, of which the leading end is held-to the cylinder by a leading-end plate-clamp 21 comprising a lower clamp bar 22 and an upper clamp bar 23. The lower bar 22, and thus the clamp 21 as a whole, is held in a groove 24 formedin and extending the length of the shell 17. The exact position of the clamp 21, and thus the position of printing matter (not shown) on the plate circumferentially and axially; with respect to the cylinder 15 is governed by a register pin 25 carried by the cylinder 15. This pin 25 enters a register hole 26 formed in an appropriate portion of the bar 22 of the clamp 21. The upper bar'23 is held to the lower bar 22 by a plurality of spaced, counter-sunk screws 27.

The ineansifor holding the clamp 21 in the groove 24 comprises a plurality of spaced screws 28 which are screwed through threaded" holes formed in a hook shaped portion of the plate cylinderlS. The front end of these screws engage an inclined edge 29 formed on the leading edge of the lower clamp bar 22. It will be apparent that tightening of the screws 28 not only forces the clamp bar 22 against an edge 30 formed on the cylinder 15, but, due to the incline 29 and a recess 31 formed in the shell 17, also retains the bar 22 and thus the Whole clamp 21 on the cylinder 15.

From the clamp 21 the flexible printing plate 20 is wrapped in a clockwise direction around the cylinder shell 17. The trailing end of the plate 20 is tensioned and/or locked to the cylinder by a tensioning mechanism comprising a plurality of tensioning plate clamps that are spaced longitudinally of the cylinder 15, there being three tensioning clamps 141 However, itwill be understood that any suitable number of clamps may be employed depending on the length of the printing cylinder 15 and the axial length of the plate 20. Since the tension clamps 14ll14'1i14ti are identical, only one will be described in detail. Each clamp has a substantially radially disposed, lower jaw plate 141 and an upper jaw plate 148. The inner end of the jaw plate 141 is fulcrumed on a rod 142 which extends axially of the cylinder 15 and which is supported by passing'through apertures in the end discs 1616', as well as by passing through apertures formed in the'pair of lugs 144144144 formed integral with the shell -17 and extending substantially radially inside thereof. The jaw plate 141 has an aperture 143 and the plate 141 extends substantially radially outwardly from the rod-142 and the free end of the plates 141 is spaced just a short distance below the outer circumference of the cylinder 15. The jaw plate 141 is substantially in the form of a rectangular plate, and the outer or free end of the plate acts as a clamping surface 145. A pair of spaced lugs 146.-146 extend at right angles to the jaw plate 14.1 adjacent the free end thereof and both of the lugs are apertured to accommodate a pivot pin 147, the latter extending parallel to and spaced from the jaw plate 141.

The pin 147 acts as the pivot for the upper jaw plate 148, the main portion of which is in the form of a rectangular plate of smaller size than the plate 141 and having an upper clamping dog 149 that extends outwardly from one end of the-plate 148 and substantially normal thereto. The plate-148, being pivoted as it is to the plate 141, is positioned adjacent one side of the plate 148 and, in the position shown in Fig. 2, the two plates are substantially chine.

parallel. A helical compression spring 153 is imbedded in recesses formed in adjacent portions of the plate 141 and 148, thus the spring 153 exerts a force that tends to separate the plates 14-1 and 148. A clamping surface is formed on the dog 149 and is positioned opposite the clamping surface 145. Thus the clamping surface 151% cooperates with the previously described clamping surface 145 of the plate 141 to grip the trailing end of the printing plate 20. The main body portion of each jaw plate 148 is indicated by the numeral 151, and this portion is provided with an aperture 152 later to be discussed.

The plate cylinder carries an oscillatory or turnable shaft 155 that extends the fuil length of the cylinder and is parallel to the axis thereof. The shaft 155 is located on the side of the lower jaw plate 141 which is remote from the side thereof to which the upper jaw plate 148 is adjacent. Opposite ends of the shaft 155 are journaled in the end discs 1616' and intermediate portions of the shaft 155 are journaled in the lugs 144-144, similar to that shown and described in Patent No. 2,694,976 supra. The shaft 155 is provided with a plurality of slots or notches 156, the number of slots 156 being equal to the number of tensioning clamps 140.

A spring rod 157 passes through each of the apertures 152 in each upper jaw plate 143 and also passes through the aperture 143 formed in the plate 141. One end of each spring rod 157 is fulcrumed on a pin 158 that is embedded in slots 156 formed in the shaft 155, there being one slot for each tensioning clamp 140. Each pin 158 is held in place by a pair of screws 160-160 that enter threaded holes radially formed in the shaft 155. A helical spring 162 surrounds the rod 157 and is compressed between a shoulder 163 formed on the end of the rod 157 and a spring receiving recess 164 formed in the side of the upper plate 148 that is adjacent to the lower plate 141.

A pin 165 passes transversally through the free end of the spring rod 157, it being noted that the pin 165 is on the side of the plate 145 that is remote from the spring recess 164, thus the pin 165 is adjacent to the face remote from the plate 141. The pin 165 engages one face (Fig. 2) of the plate 148 and thus prevents the plate 148 from passing over the end of the rod 157. The pin 165 also preloads the spring 162 which along with the rod 157 passes through the aperture 143 in the plate 141.

The mechanism for moving the free end of the block 114, and thus tensioning the plate 25, includes the os cillatory or rotary shaft 155 that extends the full length of the cylinder 15, the axis of the shaft 155 being parallel to the axis of the cylinder 15. Opposite ends of the shaft 155 are journaled in the end discs 116-16 and intermediate portions of the shaft 155 are journaled in holes 145%: in the lugs or bosses 144-144. The shaft 155 is provided with a pluralit in this case three, slots or notches 156.

As best seen in Figs. 1 and 3, the shaft 155 carries, on its right end a plurality of worm teeth 171 that do not extend around the complete circumference of the shaft 155. The teeth 171 are in mesh with a worm 172 positioned in a substantially radially disposed hole 173 formed in the end disc 15. The worm 172 is held in place by having a lower journal 175 journaled in a bearing 176, and by means of an upper journal 17% supported in a screwed bushing 179 held by threads 1811. An extension of the upper journal 17% is squared and maybe engaged by a T-wrench 182 shown in dash-dot lines in Fig. 3. The

.end thrust of the worm 172 is taken by a pair of washers 183183.

The operation of the hereinbefore described plate lockup mechanism is as follows:

When it is desired to apply a flexible printing plate to the surface of the cylinder 15 the wrench 182 is attached to the squared-end of journal 1715 and the worm 172 and worm gear 171 are turned until the spring rod 157 moves inwardly against the pressure of the pie-loaded spring N2. This opens the jaws of jaw plates 141--148 as shown in Fig. 5. Then the leading end of the printing plate 26 is secured by means of the plate clamp 21 and screws 27. The printing plate 20 is then wrapped around the cylinder and the trailing end of the plate is placed between the clamping surfaces and 150. Turning of the T-wrench 182 rotates the worm 172, the gear 171 and the shaft 155, the latter in a clockwise direction (Fig. 3). This causes the spring rod 157 and the spring 162 to move toward the right as seen in Fig. 3, thereby separating the plates 141 and 148 about the pivot 147. first cioses the clamping surfaces 145 and and grips the trailing edge of the plate 20. When the jaws are fully closed further clockwise rotation (Fig. 3) of shaft causes the plate 141, which of course carries the plate 148, to rotate about the rod 142. This results in the tensioning of the plate 20 and at the same time causes maximum compression of the spring 162.

From the above, it will be seen that the spring 162 is comparatively small and stiff. This provides a very high tension in the printing plate 20. Since there are a pinrality of spring biased plate clamps 140 positioned across the cylinder, it will be understood that the printing plate 20 is subjected to uniform tension for its entire width. To unlock the plate 20, the shaft 155 is rotated counter clockwise (Fig. 2) which in turn releases the spring tension when pin engages the outer surface of the clamp plate 148. As the shaft 155 is turned and the pin 165 moves, the tension exerted on the plate 20 is first removed, then the spring 153 is compressed and the plate 148 is moved about its fulcrum 147 to open the clamping surfaces 145 and 151 .When the clamp plates 148 abuts against the plate 141, and the latter against the trailing edge of the gap 13 the trailing end of the plate 20 is fully released.

From the foregoing it will be noted that the instant invention provides a plate lock-up mechanism for printing machines in which the spring, that tensions the plate, is under maximum compression when it is performing these operations.

Having thus set forth the nature of my invention, what I claim and desire to secure by Letters Patent of the United States is:

1. A printing cylinder plate clamp arrangement for gripping and tensioning a flexible plate, of which one end is fixedly secured to the cylinder, said arrangement comprising a control shaft in the cylinder extending parallel to the cylinder axis and a clamp mounted in the cylinder for control by said control shaft; said clamp comprising a clamp jaw plate mounted for limited bodily movement between clamping and releasing positions; a cooperating jaw member mounted on said plate, a loaded compression spring bearing on said member to move the jaw member to a limiting position in which its jaw closes against said jaw plate and in which position the spring thrust urges said jaw plate and member as a unit in the plate tensioning direction, a control rod connected to said shaft and having a formation engaging said spring to increase the compression of the latter in one direction of rotation of said shaft, and means on the rod for pulling said member and said jaw plate against the spring force in the other direction of rotation of said shaft; whereby in the plate gripping and tensioning position the spring is in its state of maximum compression.

2. A printing cylinder plate clamp arrangement for gripping and tensioning a flexible plate, of which one end is fixedly secured to the cylinder, said arrangement comprising a control shaft in the cylinder extending parallel to the cylinder axis and a plurality of spaced clamps pivotally mounted in the cylinder for control by said control shaft; each clamp comprising a radially disposed clamp jaw plate pivotally mounted for limited bodily movement on an axis inwardly of the cylinder surface, a cooperating jaw lever pivoted on said plate outwardly of said plate axis and having an operating tail portion extending inwardly of its pivot, a loaded compression spring hearing at one of its ends on said tail portion to pivot the jaw lever to a limiting position in which its jaw closes against said jaw plate and in which position the spring thrust urges said jaw plate and lever as a unit in the plate tensioning direction, a control rod connected to said shaft and passing through said lever and having a formation engaging the other end of said spring to increase the compression of the latter in one direction of rotation of said shaft, and means on the rod for pulling said tail portion and said jaw plate against the spring force in the other direction of rotation of said shaft; whereby in the plate gripping and tensioning position the spring is in its state of maximum compression.

References Cited in the file of this patent UNITED STATES PATENTS Tallent et al. July 3, 1917 Meyer Oct. 11, 1932 Jacobson June 13, 1933 Poppe Mar. 10, 1936 Tomlin Oct. 13, 1936 Lang Aug. 3, 1937 Read Dec. 2, 1941 Huck May 25, 1943 Tollison et a1. June 21, 1949 Bruns Feb. 19, 1952 Chase et a1 May 26, 1953 

